They act mostly in the tissues AND are in the bloodstream only for transport. Blood normally contains 5,000-10,000 leukocytes per cu mm.
主要在机体组织内行使功能，白血球只因正在运送过程而出现在血流中。正常成人每毫升血液中含有5,000～10,000个白血球。

To remove (a heavy metal, such AS lead or mercury) from the bloodstream by means of a chelate, such AS EDTa.
用螯合剂(如乙二胺四乙酸)从血管中去除(重金属,如铅或汞).

A procedure FOR removing metabolic waste products or toxic substances from the bloodstream by dialysis.
血液透析，血液渗析通过渗析或透析把新陈代谢产生的废物排出血流的过程

Both HDL and LDL, low density lipoprotein, are transporters of cholesterol, clearing the stuff out of your bloodstream and depositing it elsewhere
高浓度脂蛋白和低浓度脂蛋白都是胆固醇的运输者，能从你的血液中将胆固醇清除并另置他处。

But once the infection IS over, antibodies remain in the bloodstream to protect against future attack
但是一旦感染过后，抗体即留在血液中以防备将来再次的袭击。

When the mosquito bites, it releases the sporozoites, which enter human liver cells through the bloodstream and reproduce asexually
蚊虫叮咬人的时候就释放出子孢子，它通过血流进入肝细胞，并且进行无性生殖。

But once the infection is.over, antibodies remain in the bloodstream to protect against future attack
但是一旦感染过后，抗体即留在血液中以防备将来再次的袭击。